Ultrasound Transducer Array Interconnect

ABSTRACT

An apparatus ( 100 ) comprises a probe ( 102 ) including a transducer array ( 108 ) with a plurality of elements ( 110 ), a communications interface ( 112 ), and an interconnect ( 114 ) configured to route electrical signals between the plurality of elements and the communications interface. The interconnect includes a flexible printed circuit with a first surface with a first metal layer ( 406, 1210   1 ), a second opposing surface with a second metal layer ( 408, 1210   2 ), a first end ( 432, 1305 ), and a second opposing end ( 434, 1307 ). The apparatus further includes traces ( 430, 440, 1304, 1306, 1502, 1804 ) configured to readout signals from at least one of the first and second opposing ends.

TECHNICAL FIELD

The following generally relates to an ultrasound transducer array andmore particularly to an electrical interconnect for a transducer array,and is described with particular application to ultrasound imaging, butis amenable to other ultrasound applications.

BACKGROUND

Two-dimensional (2-D) ultrasound imaging is limited in its ability toreveal three-dimensional (3-D) anatomy. Three-dimensional imagingimproves qualitative and quantitative characterization relative to 2-Dimaging, but comes with the cost of increased complexity in thetransducer, imaging algorithms, data processing, display, etc.Three-dimensional imaging can be accomplished through a linear (1-D)transducer array that is swept mechanically across an area or a matrix(2-D) array that is used with electronic steering.

A 1-D transducer array is limited by the mechanical sweep speed. A 2-Darray uses electronic sweeping, which enables faster and more flexibleimaging techniques. Ideally, all elements in the matrix are usedindependently for transmitting and receiving. For a square array with Nelements along each edge, this requires N*N electrical connections,which can be challenging to manage from manufacturability, ergonomics,signal integrity, and data analysis perspectives. Further, theelectrical characteristics of each small element become difficult tomatch efficiently to a transmitter and receiver.

Row-column addressing is an alternative approach to 2-D arrays thatreduces channel count (2*N instead of N*N) and improves electrical match(at the cost of imaging flexibility). In this approach, electrodes onone surface of the active layer tie together all matrix elements alongeach row, and electrodes on the opposite surface tie together theelements along each column. This array can be used to transmit in onedirection and receive in the orthogonal direction. The literature hasdiscussed both piezoelectric (PZT) and capacitive micromachinedultrasonic transducers (CMUT) based row-column array configurations.

An interconnect circuit electrically connects the elements of thetransducer array to electronics on printed circuit boards (PCBs) in thehandle of the probe. Unfortunately, interconnects for CMUT row-columnarrays include large, rigid PCBs, which are not suitable for commercialmedical ultrasound probes, at least since their large size would makethe probe ergonomically infeasible. Furthermore, it is challenging tomanage the row and column connections in a way that facilitatesmanufacturability.

With PZT row-column arrays, electrodes patterned on both surfaces of apiezoelectric layer render the electrical interconnect complex. Oneapproach is to solder wires to both surfaces. Unfortunately, this isinconvenient at least because of the way the piezoelectric layer needsto be supported underneath the soldering point. Another approach is tobond a circuit onto both sides of the active layer. Unfortunately, thecircuit covering the piezoelectric patient-facing surface would causesignificant acoustic performance compromises.

Ultrasound imaging systems can leverage multi-row transducer arrays toimprove image quality. Older one-dimensional arrays have a single row oftransducer elements in the azimuth direction. In multi-row arrays,however, several parallel one-dimensional arrays are aligned in theelevation direction, where each parallel array constitutes a row of thetotal array. By operating the rows independently, the acoustic field canbe controlled more precisely, which enables image quality improvement.In specific, the multiple rows can be used to make the elevation slicethickness consistent through a long depth range.

However, the fabrication of such devices is considerably morecomplicated. In 1-D arrays, small wires can be attached to each elementalong the middle, one end or both ends of the element. In each case,there is only one row of wires to manage. Another approach bonds acircuit behind the active layer. If the former approach were extended toa multi-row array, multiple rows of wires would also be required, and itwould be difficult and time-consuming to manage all the wires withoutallowing them to short to each other. If the latter approach wereextended to a multi-row array, it would be difficult to connectindependently to each row of the array without contacting the otherrows.

SUMMARY

Aspects of the application address the above matters, and others.

In one aspect, an apparatus comprises a probe including a transducerarray with a plurality of elements, a communications interface, and aninterconnect configured to route electrical signals between theplurality of elements and the communications interface. The interconnectincludes a flexible printed circuit with a first surface with a firstmetal layer, a second opposing surface with a second metal layer, afirst end, and a second opposing end. The apparatus further includestraces configured to readout signals from at least one of the first andsecond opposing ends.

In another aspect, an ultrasound imaging system includes a probe with asingle flexible printed circuit configured to route electrical signalsbetween elements of a transducer array of the probe and a communicationsinterface of the probe, wherein the single flexible printed circuitincludes two metal layers and route signals off the single flexibleprinted circuit at opposing ends of the single flexible printed circuit.The ultrasound imaging system further includes an ultrasound device witha transmit circuit that controls transmission by the transducer array, areceive circuit that controls reception by the transducer array, and anecho processor that processes echoes receive by the transducer array.The ultrasound imaging system further includes a complementarycommunications interface electrically connecting the communicationsinterface of the probe and the ultrasound device.

In another aspect, a method includes transmitting an ultrasound signalwith a transducer array of an ultrasound imaging probe. The transducerarray includes one of a 2-D row-column addressed capacitivemicromachined ultrasonic transducer array, a 2-D row-column addressedpiezoelectric transducer array, or a multi-row transducer array. Themethod further includes receiving echoes with the transducer array. Themethod further includes generating signals indicative of the receivedechoes with the transducer array. The method further includes routingthe signals from the transducer array to a communications interface ofthe probe with an interconnect, wherein the interconnect includes asingle flexible printed circuit with no more than two metal layers andconfigured to route the signals at no more than two opposing ends of thesingle flexible printed circuit. The method further includes processingthe signals, generating data indicative thereof.

Those skilled in the art will recognize still other aspects of thepresent application upon reading and understanding the attacheddescription.

BRIEF DESCRIPTION OF THE DRAWINGS

The application is illustrated by way of example and not limitation inthe figures of the accompanying drawings, in which like referencesindicate similar elements and in which:

FIG. 1 schematically illustrates an example ultrasound system with atransducer array electrically coupled to a single flexible printedcircuit interconnect that has two metal layers located on opposing sidesthat route signals in opposing directions;

FIGS. 2, 3, 4 and 5 schematically illustrate an example in which thetransducer array is a row-column addressed CMUT based transducer array;

FIGS. 6 and 7 schematically illustrate an example in which the singleflexible printed circuit interconnect is folded back behind the CMUTtransducer array;

FIGS. 8-11 schematically illustrate an example in which the transducerarray is a row-column addressed PZT based transducer array;

FIG. 12 schematically illustrates an example in which the transducerarray is a multi-row transducer array;

FIGS. 13 and 14 schematically illustrate an example in which theinterconnect for the multi-row transducer array reads signals from aninner row of elements out from one side of the interconnect and combinesand reads signals from two outer rows of elements out from an opposingside of the interconnect;

FIGS. 15, 16 and 17 schematically illustrate an example in which theinterconnect for the multi-row transducer array reads signals from aninner row of elements out from one side of the interconnect andindependently reads signals from two outer rows of elements out from anopposing side of the interconnect;

FIGS. 18 and 19 schematically illustrate an example in which theinterconnect for the multi-row transducer array independently readssignals from two rows of elements out from one side of the interconnectand independently reads signals from three rows of elements out from anopposing side of the interconnect;

FIG. 20 schematically illustrates an example method for a row-columnaddressed CMUT or PZT based transducer array; and

FIG. 21 schematically illustrates an example method for a row-columnaddressed multi-row transducer array.

DETAILED DESCRIPTION

FIG. 1 schematically illustrates an ultrasound (US) system 100. Theultrasound system 100 includes a probe 102 and an ultrasound device 104.Data and/or control signals are conveyed between the probe 102 and theultrasound device 104 via a communication channel 106 such as a cable,radio frequency, etc. For example, in one instance the probe 102 and theultrasound device 104 have complementary communications interfaces 112and 113, and communicate with each other, over a hard wire and/orwirelessly, via the communication channel 106 and the complementarycommunications interfaces 112 and 113.

The probe 102 includes a transducer array 108 that includes a pluralityof transducer elements 110 and an interconnect 114 which electricallyconnects the plurality of transducer elements 110 and the complementarycommunications interface 112. In one non-limiting instance, thetransducer array 108 is a 2-D row-addressed CMUT or PZT transducerarray. In another instance, the transducer array 108 is a multi-rowtransducer array. In both instance, the interconnect 114 includes asingle flexible printed circuit with only two metal layers. As describedin greater detail below, traces of the single flexible printed circuitare in both of the two metal layers, which are located on opposing sidesof the single flexible printed circuit, and readout signals fromopposing ends of the single flexible printed circuit. It is to beappreciated that the trace patterning approaches described hereinfacilitate maintaining performance and/or manufacturability, and/orprovides efficient and/or cost-effective fabrication. In general, theapproached described herein may allow for using as few metal layers aspossible while managing traces to optimize manufacturing and minimizecost and maintain acoustic performance.

The ultrasound device 104 includes a control and/or processing portion116, a user interface 118, and a display 120. The control and/orprocessing portion 116 includes transmit circuitry 122 that controlsexcitation of the elements 110 and receive circuitry 124 that controlsreception of echo signals by the elements 110. The control and/orprocessing portion 116 further includes an echo processor 126 thatprocesses received echo signals. Such processing may include beamforming(e.g., delay and sum, etc.) and/or otherwise processing the echosignals, e.g., to lower speckle, to improve specular reflectordelineation, to filter the echo signals via FIR and/or IIR filters, etc.

The control and/or processing portion 116 further includes a controller128 that controls the transmit circuitry 122, the receive circuitry 124,and the echo processor 126. Such control may include controlling theframe rate, transmit angles, energies and/or frequencies, transmitand/or receive delays, processing of echo signals, the imaging mode,etc. The control and/or processing portion 116 further includes a scanconverter 130 that coverts processed echo signals and generates data fordisplay. The display 120 visually presents the scan converted data, andthe user interface 118 includes input controls and/or output displaysfor interacting with the system 100.

In the illustrated embodiment, the probe 102 and the ultrasound device104 are separate entities. The probe 102 includes structure which housesthe transducer array 108 and the interconnect 114. This may includephysically supporting and/or enclosing one or more of the transducerarray 108 and the interconnect 114. The ultrasound device 104 includesstructure which houses at least the transmit circuitry 122, the receivecircuitry 124, the processor 126, the controller 128 and the scanconverter 130. In one instance, the ultrasound device 104 is a computeror computing system. The user interface 118 and/or the display 120 canbe part of the ultrasound device 104 (as shown) or separate entitiesconnected thereto.

Alternatively, the probe 102 and the ultrasound device 104 are part of asame physical structure such as a single enclosure or housing. Such aconfiguration may be part of a hand-held or other ultrasound apparatus.A hand-held ultrasound apparatus may utilize internally located power,e.g., from a power source such as a battery, a capacitor, etc. to powerthe components therein, and/or power from an external power source. Anexample of a hand-held device is described in U.S. Pat. No. 7,699,776,entitled “Intuitive Ultrasonic Imaging System and Related MethodThereof,” and filed on Mar. 6, 2003, which is incorporated herein in itsentirety by reference.

FIGS. 2-5 schematically illustrate an example in which the transducerarray 108 includes a row-column addressed CMUT chip 402 and theinterconnect 114 includes a single flexible printed circuit 404 with atop side 406 and a bottom side 408 and only two metal layers withreadout signals from opposing ends. In this embodiment, both the rowsand the columns are addressed from a same side (i.e. the top side 406)of the row-column addressed CMUT chip 402.

FIG. 2 shows a perspective view looking onto the top side 406 with aninstalled CMUT chip 402. FIG. 3 shows a perspective view looking ontothe top side 406 with the chip 402 separated therefrom. FIG. 4 shows aperspective view looking onto the top side 406 without the chip 402 andwith traces on the bottom side 408 the location thereof visible throughthe top side 406. FIG. 5 shows a perspective view looking onto thebottom side 408 without the chip 402 and with traces on the top side 406the location thereof visible through the bottom side 408.

For sake of brevity and clarity, the illustrated row-column addressedCMUT chip 402 is discussed in connection with four columns and four rows(i.e., a 4×4 square matrix). However, it is to be understood that therow-column addressed CMUT chip 402 could include 8×8, 16×16, 32×32,192×192, 512×512, etc. rows and columns, and/or have a non-squareconfiguration such as a rectangular, circular and/or other shapedconfiguration. An example geometry for a 62×62 square matrix configuredfor an abdominal scan can be one inch by one inch. Other geometries andapplications are contemplated herein.

The illustrated row-column addressed CMUT chip 402 includes a pluralityof electrodes along each of the edges with a total of sixteenelectrodes, including four on each edge, with electrodes 410 on a firstside or edge 412, electrodes 414 on a second side or edge 416 whichopposes the first side 412, electrodes 418 on a third side or edge 420which is transverse and adjacent to and between the first and secondsides 412 and 416, and electrodes 422 on a fourth side or edge 424 whichopposes the third side 420.

The top side 406 includes a metal layer with a plurality of pads 426,428 and traces 430. The pads 426 are disposed adjacent to the electrodes410 and 414 on sides 436 and 438 of the interconnect 114. The traces 430extend from adjacent to the third and fourth sides 420 and 424 of thechip 402 to ends or sides 432 and 434 of the interconnect 114. A sub-setof the pads 428 are disposed adjacent to the traces at the end 432, andanother sub-set of the pads 428 are disposed adjacent to the traces atthe end 434.

The bottom side 408 includes a second metal layer with a plurality oftraces 440 that extend from the pads 426 of the top side 406 along thesecond side 408 to the pads 428 on the top side 406. A sub-set of thetraces 430 extends to the end 432, and another sub-set of the traces 430extends to the end 434. The traces 440 electrically connect to the pads426 and the pads 428 on the top side 406 through vias and/or the like.Signals are read out from only the two opposing sides 432 and 434 viathe pads 428 and the traces 430.

Discrete electrically conductive wires 442 are bonded to the CMUT chipelectrodes 410, 414, 418 and 422 and the corresponding electrode pads426 and/or traces 430 on the first side 406 of the flexible printedcircuit 404. In the illustrated embodiment, the discrete electricallyconductive wires 442 are staggered odd/even between opposing sides forboth the rows and the columns. This may ease manufacturability and/orreduce cross-talk. The wires 442 can be soldered, wire-bonded, etc.

Organizing electrical connections (e.g., the traces 430 and 440) asdescribed herein can facilitate assembly and/or enable ergonomics, e.g.,by the use of only two legs of the flexible circuit (i.e., ends 432 and434) that extend from opposite (non-adjacent) edges of the array. Thesingle flexible printed circuit 404 connects to the active transducermaterial and employs a unique routing technique, which can minimize thenumber of circuit layers required to connect each row and column of thearray.

In general, the single flexible printed circuit 404 is not configuredfor only the specific row-column addressed CMUT chip 402. Rather, thesingle flexible printed circuit 404 is compatible with any row-columnaddressed CMUT chip where the electrical connection pads are on thepatient surface of the row-column addressed CMUT chip, regardless ofwhether the CMUT is fabricated with sacrificial release, wafer bonding,or some other technique.

In a variation, the signals are read out from only one side (e.g., theside 432 or the side 434). This can be achieved by having all of thetraces 430 and 440 extend from adjacent to a respective side of the chip402 to only the edge 432 or 434. In another variation, signals are readout from adjacent sides 432 and 436 or 438, or 434 and 436 and/or 438.In yet another variation, signals can be read out from three or all fourof the sides 432, 434, 436 and/or 438. In another still variation, theinterconnect 114 includes two or more flexible printed circuit and/orthree or more metal layers per flexible printed circuit.

FIGS. 6 and 7 show an example where the single flexible printed circuit404 is flexed such that the signal traces 430 and 440 (indicated bydashed lines with arrow heads) are redirected back behind the row-columnaddressed CMUT chip 402 by bending the single flexible printed circuit404. A rigid piece of stiffener material 602 (e.g., FR-4) can be placedon the bottom side 406 of the single flexible printed circuit 404 underthe row-column addressed CMUT chip 402 to provide stability, e.g.,during chip mounting and/or otherwise.

A larger backing block can be bonded to the back side of the stiffener.Due to the operation of the row-column addressed CMUT chip 402, thisblock would not have significant influence on the acoustics of thedevice and provides mechanical reference for positioning and/orhandling. Expose edges of the backing block can make is easy to handlethe assembly, e.g., to glue it into a housing of the probe 102.

The interconnection can be made in multiple directions inthree-dimensional space. The single flexible printed circuit 404electrically connects the row-column addressed CMUT chip to thecommunications interface 112 (FIG. 1), which, again, can be in thehandle and/or elsewhere of the probe 102 (FIG. 1).

FIGS. 8-11 schematically illustrate an example in which the transducerarray 108 includes a row-column addressed PZT chip 802.

This configuration is similar to the configuration discussed inconnection with FIGS. 2-5 except the rows and columns are addressed fromdifferent and opposing sides 804 and 806 of the PZT chip 802, with oneof the row or columns addressed through conductive strips on the (top)side 804 of the chip 802, which faces away from the single flexibleprinted circuit 404, and the other of the row or columns addressedthrough electrically conductive strips on the (bottom) side 806 of thechip 802, which faces the single flexible printed circuit 404.

Furthermore, unlike in the configuration discussed in connection withFIGS. 2-5, the traces 430 include sub-portions 808 that extend on thetop side 406 and on a location under an installed row-column addressedPZT chip 802. With this embodiment, the electrically conductive stripson the bottom side 806 of the row-column addressed PZT chip 802 arebonded through an adhesive or the like to the sub-portions 808 of thetraces 430, which electrically connects the rows or the columns to thesingle flexible printed circuit 404.

The other of the rows or the columns, which are addressed from the topside 804, are electrically connected the pads 426 with the discreteelectrically conductive wires 442 like in FIGS. 2-5. In FIG. 11, thesingle flexible printed circuit 404 includes wings 1102, which extend orprotrude out from sides 436 and 438 and that are configured to flex andcurl around the top side 804 and electrically connect with theelectrically conductive strips thereon through an adhesive. Anacoustically-beneficial matching layer(s) can be applied to a remainingportion of the top side 804.

Organizing electrical connections (e.g., the traces 430 and 440) asdescribed herein can facilitate assembly and/or enable ergonomics, e.g.,by the use of only two legs of the flexible circuit (i.e., ends 432 and434) that extend from opposite (non-adjacent) edges of the array. Thesingle flexible printed circuit 404 connects to the active transducermaterial and employs a unique routing technique, which can minimize thenumber of circuit layers required to connect each row and column of thearray. The single flexible printed circuit 404 is not configured foronly the row-column addressed PZT chip 802.

In a variation, the signals are read out from only one side (e.g., theside 432 or the side 434), e.g., as discussed in connection with FIGS.2-5. Likewise, in another variation, signals can be read out fromadjacent sides 432 and 436 or 438, or 434 and 436 and/or 438, or signalscan be read out from three or all four of the sides 432, 434, 436 and/or438. Furthermore, in another variation, the interconnect 114 includestwo or more flexible printed circuits and/or three or more metal layers.A backing block can be used as a mechanical function (as in the CMUTconfiguration) and an acoustical function (e.g., attenuating sound thatis transmitted into it).

FIG. 12 shows a perspective view of an example in which the transducerarray 108 includes a multi-row transducer 1200 and the interconnect 114.It is to be appreciated that the interconnect 114 can be extended toother architectures such as a multi-layer ceramic as discussed in U.S.Pat. No. 6,971,148 to Mohr et al., layers with curved surfaces acrosselevation as discussed in U.S. Pat. No. 5,651,365 to Hanafy et al., orarrays with ground electrode that wraps around the edges of the ceramicinstead of using a ground foil.

The multi-row transducer 1200 includes an acoustic lens 1202, anacoustic impedance matching layer(s) 1204, a ground foil 1206, an activelayer 1208 (e.g., piezoelectric ceramic), the interconnect 114 whichincludes a flexible printed circuit 1210 with top and bottom layers 1210₁ and 1210 ₂, and a backing block 1212. The active layer 1208 includesthree rows 1208 ₁, 1208 ₂ and 1208 ₃ in an elevation direction 1214,each row including a plurality of elements (not visible) in an azimuthdirection 1216. Columns of elements 1218 ₁, 1218 ₂, 1218 ₃, 1218 ₄, 1218₅, and 1218 ₆ span the rows 1208 ₁, 1208 ₂ and 1208 ₃. Other embodimentsinclude more or less rows and/or columns of elements.

FIG. 13 schematically illustrates pad placement and trace routing of theflexible printed circuit 1210 for the configuration of FIG. 12. The toplayer 1210 ₁ of the flexible printed circuit 1210 includes sets of pads1302 ₁, 1302 ₂ and 1302 ₃, one set respectively for each of the elementsof each of the rows 1208 ₁, 1208 ₂ and 1208 ₃. The bottom layer 1210 ₂of the flexible printed circuit 1210 includes a first set of traces 1306at one end 1307 and electrically connected to the pads 1302 ₂ for themiddle row 1208 ₂ (FIG. 12), and a second set of traces 1304 at anopposing end 1305 and electrically connected to both the pads 1302 ₁ and1302 ₃ for the two outer rows 1208 ₁ and 1208 ₃ (FIG. 12).

FIG. 14 shows a magnified view of traces 1304 of FIG. 13. A pair oftraces 1304 ₆ and 1306 ₆ runs parallel to each other and under pads 1302_(3,6) and 1302 _(2,6,) a pair of traces 1304 ₅ and 1306 ₅ runs parallelto each other and under pads 1302 _(3,5) and 1302 _(2,5,) a pair oftraces 1304 ₄ and 1306 ₄ runs parallel to each other and under pads 1302_(3,4) and 1302 _(2,4,) a pair of traces 1304 ₃ and 1306 ₃ runs parallelto each other and under pad 1302 _(2,3,) a pair of traces 1304 ₂ and1306 ₂ runs parallel to each other and under pad 1302 _(2,2,) and a pairof traces 1304 ₁ and 1306 ₁ runs parallel to each other and under pad1302 _(2,1).

With reference to FIGS. 13 and 14, vias 1308 connect the pads 1302 ₁ forthe outer row 1208 ₁ (FIG. 12) to the traces 1304, and vias 1310 connectthe pads 1302 ₃ (e.g., the pads 1302 _(3,6), 1302 _(3,4,) and 1302_(3,5)) for the other outer row 1208 ₃ (FIG. 12) to the same traces 1304(e.g., the traces 1304 ₆, 1304 ₅ and 1304 ₃ in FIG. 14). Thisconfiguration electrically connects the elements of the two outer rows1208 ₁ and 1208 ₃. Vias 1312 connect the pads 1302 ₂ (e.g., the pads1302 _(2,1)-1302 _(2,6) in FIG. 14) for the middle row 1208 ₂ (FIG. 12)to the traces 1306 (e.g., the traces 1306 ₁-1306 ₆).

This configuration represents symmetric row connections. For thisconfiguration, a pitch of the traces 1304 and 1306 are less than half apitch of the pads 1302 in order to fit pairs of the traces 1304 and 1306side-by-side under each pad of the pads 1302 and hence under each of thetransducer elements. In one instance, current state of the artapproaches can be used for low-frequency and/or large pitch designs thatare used for deep imaging on obese patients. Other approaches are alsocontemplated herein.

FIG. 15 shows a variation of the configuration of FIG. 14 in which thetwo outer rows 1208 ₁ and 1208 ₃ are not electrically connected to thesame traces. As described above, the vias 1308 connect the pads 1302 ₁for the outer row 1208 ₁ (FIG. 12) to the traces 1304. However, in thisvariation, the vias 1310 connect the pads 1302 ₃for the other outer row1208 ₃ (FIG. 12) to traces 1502. With this variation, each row can beelectrically controlled completely independent of its mirror row. Thisenables increased control over the elevation focus characteristics,allowing steering in elevation.

FIG. 16 shows a magnified view of a sub-section 1504 of FIG. 15. A pairof traces 1502 and 1306 runs parallel to each other and under pads 1302₃ with vias 1310 electrically connecting the pads 1302 ₃ and the traces1502. The traces 1306 also run under pads 1302 ₂ with vias 1312electrically connecting the pads 1302 ₂ and the traces 1306. FIG. 17shows a magnified view of a sub-section 1506 of FIG. 15. The traces 1306run and under pads 1302 ₂ with vias 1312 electrically connecting thepads 1302 ₂ and the traces 1306, and the traces 1304 run under pads 1302₁ with vias 1308 electrically connecting the pads 1302 ₁ and the traces1304.

FIG. 18 shows variation of the flexible printed circuit 1210 of FIG. 12for a configuration in which the active layer 1208 includes five rows ofelements, including the rows 1208 ₁-1208 ₃ discussed above (FIG. 12) andtwo additional rows which are located outside of the rows 1208 ₁ and1208 ₃ respectively sandwiching them between rows 1208 ₀ and 1208 ₂ andbetween rows 1208 ₂ and 1208 ₄. In this instance, the flexible printedcircuit 1210 includes two additional sets of pads 1302 ₀ and 1302 ₄respectively for the two additional rows of elements.

FIG. 19 shows a magnified view of a sub-section 1802 of FIG. 18. Forthis configuration, the traces 1306 run under the pads 1302 ₂ with thevias 1312 electrically connecting the pads 1302 ₂ and the traces 1306,and the pair of traces 1502 and 1306 runs parallel to each other andunder the pads 1302 ₃ and 1302 ₄ with the vias 1310 electricallyconnecting the pads 1302 ₃ and the traces 1502 and the vias 1312electrically connecting the pads 1302 ₂ and the traces 1306. The pads1302 ₄ include extensions 1804 configured as traces for the pads 1302 ₄.

For the configurations of FIGS. 12-19, the interconnect 114 (i.e., thesingle flexible printed circuit 1210) makes electrical interconnect withthe active layer by discrete conductive pads on its adjacent surface.These pads contain vias to connect to the opposite surface of the singleflexible printed circuit 1210 where the majority of the signal tracesrun. Signal traces run in parallel on the opposite surface to makeoptimal use of azimuthal space under the element. This allows for thesingle flexible printed circuit 1210 to include only a minimum number oflayers (e.g., two metal layers), which minimizes acoustic impact.

Using the two-layer single flexible printed circuit 1210 bonded in aplanar configuration, sandwiched between the active layer 1208 and thebacking 1212, keeps the backing fabrication and electrical connectionprocesses simple, e.g., as opposed to embedding the interconnect intothe backing or attaching wires to individual elements. For a largernumber of rows, some traces can be run on the top surface (no viarequired), and/or the number of flex layers could be increased. Even ifthe number of layers is increased, the approach described herein stillhelps minimize the number of required layers.

FIGS. 20 and 21 illustrate methods in accordance with one or moreembodiments disclosed herein.

It is to be appreciated that the order of the following acts is providedfor explanatory purposes and is not limiting. As such, one or more ofthe following acts may occur in a different order. Furthermore, one ormore of the following acts may be omitted and/or one or more additionalacts may be added.

FIG. 20 illustrates a method for a row-column addressed CMUT or PZTtransducer array.

At 2002, a row-column addressed transducer array transmits ultrasoundsignals, receives echoes, and generates electrical signals indicative ofthe received echoes.

At 2004, the electrical signals are routed from the transducer array toa communications interface through the interconnect 114, which, in oneinstance, is a single flexible printed circuit with only two metallayers, which are located on opposing sides of the single flexibleprinted circuit, and which route the signals off the interconnect 114 inopposing directions.

At 2006, the electrical signals are further routed to processingcircuitry, which processes the signals and at least generates dataindicative thereof (e.g., an image).

FIG. 21 illustrates a method for a multi-row transducer array.

At 2102, a multi-row transducer array transmits ultrasound signals,receives echoes, and generates electrical signals indicative of thereceived echoes.

At 2104, the electrical signals are routed from the transducer array toa communications interface through the interconnect 114, which, in oneinstance, is a single flexible printed circuit with only two metallayers, which are located on opposing sides of the single flexibleprinted circuit, and which route the signals off the interconnect 114 inopposing directions.

At 2106, the electrical signals are further routed to processingcircuitry, which processes the signals and at least generates dataindicative thereof (e.g., an image).

The application has been described with reference to variousembodiments. Modifications and alterations will occur to others uponreading the application. It is intended that the invention be construedas including all such modifications and alterations, including insofaras they come within the scope of the appended claims and the equivalentsthereof.

What is claimed is:
 1. A probe, comprising: a multi-row transducer, including an active layer with three rows in an elevation direction, including an end row, a middle row and an opposing end row, wherein each of the three rows includes a plurality of elements in an azimuth direction; a communications interface; and an interconnect disposed under the multi-row transducer, the interconnect, including a flexible printed circuit configured to route electrical signals between the plurality of elements of the three rows and the communications interface.
 2. The probe of claim 1, wherein the flexible printed circuit comprises: a top layer with three sets of pads, including a first set of pads for the end row, a second set of pads for the middle row and a third set of pads for the opposing end row; and a bottom layer, including: a first end; a second opposing end; a first set of traces at the first end and electrically connected to the second set of pads for the middle row; and a second set of traces at the second opposing end and electrically connected to the first set of pads for the end row and the third set of pads for the opposing end row.
 3. The probe of claim 2, wherein a pair of traces, including a trace of the first set of traces and a trace of the third set of traces, is disposed in parallel under at least the third sets of pads.
 4. The probe of claim 3, wherein the pair of traces is entirely under the third set of pads.
 5. The probe of claim 3, further comprises: a plurality of vias, including: a first set of vias configured to connect the second set of pads for the middle row to the first set of traces; and a second set of vias configured to connect the first set of pads for the end row and the third set of pads for the opposing end row to the second set of traces.
 6. The probe of claim 5, wherein a pitch of the first and second sets of traces is less than half a pitch of the first, second and third set of pads.
 7. The probe of claim 1, wherein the flexible printed circuit comprises: a top layer with three sets of pads, including a first set of pads for the end row, a second set of pads for the middle row and a third set of pads for the opposing end row; and a bottom layer, including: a first end; a second opposing end; a first set of traces at the first end and electrically connected to the second set of pads for the middle row; a second set of traces at the second opposing end and electrically connected to the first set of pads for the end row; and a third set of traces at the second opposing end and electrically connected to the third set of pads for the opposing end row.
 8. The probe of claim 7, further comprises: a plurality of vias, including: a first set of vias configured to connect the second set of pads for the middle row to the first set of traces; a second set of vias configured to connect the first set of pads for the end row to the second set of traces; and a third set of vias configured to connect the third set of pads for the opposing end row to the third set of traces.
 9. The probe of claim 8, wherein each of the three rows is controlled independent of the other rows of the three rows.
 10. The probe of claim 8, wherein a pair of traces, including a trace of the first set of traces and a trace of the third set of traces, is disposed in parallel under the third sets of pads, wherein a trace of the first set of traces is disposed under the second sets of pads; and wherein a trace of the second set of traces is disposed under the first sets of pads.
 11. The probe of claim 1, wherein the active layer further comprises a first intermediary row dispose between the end row and the middle row and a second intermediary row disposed between the middle row and the opposing end row, and the top layer includes a fourth set of pads for the first intermediary row and a fifth set of pads for the second intermediary row.
 12. The probe of claim 11, further comprising: a fourth set of traces for the to the first intermediary row, wherein the fourth set of traces are extensions of the fourth set of pads; and a fifth set of traces for the to the second intermediary row, wherein the fifth set of traces are extensions of the fifth set of pads.
 13. The probe of claim 1, wherein the interconnect is in electrical communication with the active layer through discrete conductive pads.
 14. The probe of claim 1, wherein the flexible printed circuit include multiple layers.
 15. The probe of claim 14, further comprising: a backing, wherein the multiple layers are in a planar configuration between the active layer and the backing.
 16. The probe of claim 1, wherein the top layer includes at least one trace.
 17. A method, comprising: receiving ultrasound echo signals with a multi-row transducer of a probe, wherein the multi-row transducer includes an active layer with three rows in an elevation direction, including an end row, a middle row and an opposing end row, and each of the three rows includes a plurality of elements in an azimuth direction; generating electrical signals indicative of the received ultrasound echo signals; interconnecting, via an interconnect, the multi-row transducer with a communications interface of the probe, wherein the interconnect includes a flexible printed circuit disposed under the multi-row transducer; routing, with the interconnect, the electrical signals to the communications interface.
 18. The method of claim 17, further comprising: routing signals from the middle row to one side of the interconnect; and routing signals from the end row and the opposing end row to an opposing side of the interconnect.
 19. The method of claim 17, further comprising: routing signals from the middle row to one side of the interconnect; and routing signals from the end row and the opposing end row to different sides of the interconnect.
 20. The method of claim 17, further comprising: routing, with the communications interface, the electrical signals to processing circuitry configured to process the electrical signals and generate an image. 